From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68D05CA9EC7 for ; Sat, 2 Nov 2019 17:31:38 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id B89E42080F for ; Sat, 2 Nov 2019 17:31:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="nZuWTF4B" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B89E42080F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17252-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 17769 invoked by uid 550); 2 Nov 2019 17:31:31 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 17749 invoked from network); 2 Nov 2019 17:31:30 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=R5U6Kj8zEV9KobA96rVptQNqSLtfG2r+Wn7yLIJ/SjM=; b=nZuWTF4BuB9R9IrgYRoEbpBnjy2uh+hDRXXBWx+J+/nKCK3Q9SqQb4rGc0o2JbS78Z IGasXP4JcJlcZqvBr8jr42AoqszXdT6ZkfobJEO3q8eAMYsdFqaxFxfcOX/QrjMVv/qW Gdq8mBjWvMInhMP1k9d4nI6SG1KYp3FJBWObE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=R5U6Kj8zEV9KobA96rVptQNqSLtfG2r+Wn7yLIJ/SjM=; b=WfywrD+gqttowyjAceX3QjNZq8Khqwvdzx/SQ+RYYc1u7lbxl7c3TmMoohyhdKjqpX UX6OffG3FVGpZ5Hr8YiqDKSZOzJGz+42Xnn67xmd9HcD7nd8hrywlgqNNncp19OMIzHN m5Kf1vd1rgynCYdBfovr1aqd3e0XF9zlkcSfPZpRVUmFwB8X9Pz0Sqrg5PTGSTt59yoO JuwfyBwvNyJKDgGR0w4igtkb21HGljTi45DyrYKrqOPDvz8tf8+Ct+De4ypseljoaair +c42hN3n3+reScJsi7jFhBZbqldfvykb0a6uTt7IAE1Y5wqfVHGxewy3j7QDK6sAC+HE Nczw== X-Gm-Message-State: APjAAAU8P7gEfqFFdCfwFa0K6xQUPXmE05r9k1vAVObNI4O53g8Ea/ni OHSx4SMeuvmwFMLHgT1mrOubmQ== X-Google-Smtp-Source: APXvYqwc02Tws2pGBZl8WuCjpMDz1HN7KL0ueLxBeqsIsd4eXR/cQCznRRNO20Nh24wWyn2g8VRU7w== X-Received: by 2002:a17:902:864a:: with SMTP id y10mr18474527plt.162.1572715878210; Sat, 02 Nov 2019 10:31:18 -0700 (PDT) Date: Sat, 2 Nov 2019 10:31:15 -0700 From: Kees Cook To: Sami Tolvanen Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Laura Abbott , Mark Rutland , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 07/17] scs: add support for stack usage debugging Message-ID: <201911021030.88433384D9@keescook> References: <20191018161033.261971-1-samitolvanen@google.com> <20191101221150.116536-1-samitolvanen@google.com> <20191101221150.116536-8-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191101221150.116536-8-samitolvanen@google.com> On Fri, Nov 01, 2019 at 03:11:40PM -0700, Sami Tolvanen wrote: > Implements CONFIG_DEBUG_STACK_USAGE for shadow stacks. When enabled, > also prints out the highest shadow stack usage per process. > > Signed-off-by: Sami Tolvanen Thanks for helping me find this Kconfig. :) :) Reviewed-by: Kees Cook -Kees > --- > kernel/scs.c | 39 +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 39 insertions(+) > > diff --git a/kernel/scs.c b/kernel/scs.c > index 7780fc4e29ac..67c43af627d1 100644 > --- a/kernel/scs.c > +++ b/kernel/scs.c > @@ -167,6 +167,44 @@ int scs_prepare(struct task_struct *tsk, int node) > return 0; > } > > +#ifdef CONFIG_DEBUG_STACK_USAGE > +static inline unsigned long scs_used(struct task_struct *tsk) > +{ > + unsigned long *p = __scs_base(tsk); > + unsigned long *end = scs_magic(tsk); > + uintptr_t s = (uintptr_t)p; > + > + while (p < end && *p) > + p++; > + > + return (uintptr_t)p - s; > +} > + > +static void scs_check_usage(struct task_struct *tsk) > +{ > + static DEFINE_SPINLOCK(lock); > + static unsigned long highest; > + unsigned long used = scs_used(tsk); > + > + if (used <= highest) > + return; > + > + spin_lock(&lock); > + > + if (used > highest) { > + pr_info("%s: highest shadow stack usage %lu bytes\n", > + __func__, used); > + highest = used; > + } > + > + spin_unlock(&lock); > +} > +#else > +static inline void scs_check_usage(struct task_struct *tsk) > +{ > +} > +#endif > + > bool scs_corrupted(struct task_struct *tsk) > { > return *scs_magic(tsk) != SCS_END_MAGIC; > @@ -181,6 +219,7 @@ void scs_release(struct task_struct *tsk) > return; > > WARN_ON(scs_corrupted(tsk)); > + scs_check_usage(tsk); > > scs_account(tsk, -1); > task_set_scs(tsk, NULL); > -- > 2.24.0.rc1.363.gb1bccd3e3d-goog > -- Kees Cook